In Country C, the number of transactions made by various noncash metho

Question

https://gmatclub.com/forum/download/file.php?mode=view&id=50788 In Country C, the numbers of transactions made by various noncash methods in 2006 and 2009 are shown in the graphic. All other transactions were made with cash. If the total value of all credit card transactions in 2009 was 10% more than the total value of all credit card transactions in 2006, then the average (arithmetic mean) value of credit card transactions increased by GRAPH_1_PLACEHOLDER % from 2006 to 2009. The number of GRAPH_2_PLACEHOLDER transactions increased by 25% from 2006 to 2009. ID: 100351 Untitled1.png

Gagoosh · Accepted Answer

let the the average txns (2006) be s and txns (2009) be n.
Translating the prompt to an equation -If the total value of all credit card transactions in 2009 was 10% more than the total value of all credit card transactions in 2006, we get the below.
 20n = 22s (110/100) 
 100n=121s
 n/s = 121/100 =1.21

Calculating the increase in percentage;
(n/s - 1)100% = (1.21-1.00)100% = 21%

Hope this helps!!

(if it does, please hit kudos)

Apt0810 · Answer

Let x be total value in 2006
In 2009: 1.1x

Change in avg = (1.1x/20 - x/22)/(x/22) = 21%

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scc404 · Answer

mean x count = sum / price x quantity = revenue

let revenue = a number i.e 220 
2006 --> P x 22 (count) = 220 therefore price = 10 
to get to revenue of 2009 +10%: 220 * .10(220) = 242
2009 --> P x 20 = 242 therefore price = 242/20 = 12.1

percent change
= (12.1 - 10) / 10 
 = .21 = 21%

esonrev · Answer

Why can't we plug in numbers?

# of Transactions
2006: 105
2009: 91

Value
2006:  100 
2009:  110

110/91 = 1.21
100/105 = 0.95

(1.21-0.95)/1.21 = 0.21487603305

Why is this not the answer?

CEdward · Answer

That is the answer. You just didn't multiply by 100.

Sajjad1994 · Answer

Official Explanation

Of the four noncash methods represented in the graph, only paper check showed an increase from 2006 to 2009. Indeed, the number of paper check transactions increased from 24 million in 2006 to 30 million in 2009. This indicates a percentage increase of  (\frac{30−24}{24}) (100%)=25%.

The correct answer is paper check.

The average value of all credit card transactions in 2006 was  \frac{T}{22,000,000} , where T is the total value of all credit card transactions in 2006. If the total value of all credit card transactions in 2009 was 10% more than the total value of all credit card transactions in 2006, then the total value of all credit card transactions in 2009 was 1.1T. Therefore, the average value of all credit card transactions in 2009 was  \frac{1.1T}{20,000,000.} 
If the average value of credit card transactions increased by x% from 2006 to 2009, then

(\frac{100+x}{100})(\frac{T}{22,000,000})=\frac{1.1T}{20,000,000}

Therefore,

\frac{100+x}{100} =   \frac{(1.1)(22,000,000)}{20,000,000} 
 
  = \frac{121}{100}

Thus, 100 + x = 121, so x = 21.

The correct answer is 21.0.

GMATCoachBen · Answer

Video solution here (2:47):

https://www.youtube.com/watch?v=5JY8TUg8iiQ

egmat · Answer

This question has a relative simple chart – bar chart and the data set is easy to understanding. The only difficult part in this question is question 1 for it requires pretty significant translation and calculations. But if you read this choice by strategically pausing and neatly organize the information, the solution should become easier.

Watch the solution and identify which step you faltered at. Frankly, this question appears to be a time hog – given that students have taken more than 3’ to solve it. But if one reads the question 1 slowly and organizes information properly, it can indeed be a time saver. Also, using calculator in this question is advisable.

Another thing to observe in this question is how question 1 is calculation intensive but question 2 can be solved so efficiently through careful observation. Another place where one can save time!

So, here are the time saving techniques that you should learn from this question:
 
 Slow read the question statement by strategically pausing and organizing the information properly. 
 Don’t jump to calculations – first draw inferences through observations. 
 Use calculator when necessary.

https://www.youtube.com/watch?v=lmkrFh2onHw

devdattakhoche · Answer

How I did it: 
Let’s define the variables first:
 
 N9 = number of transactions in 2009 = 20 
 N6 = number of transactions in 2006 = 22 
 V9 = total value of transactions in 2009 
 V6 = total value of transactions in 2006  
According to the given information:
V9 = 110% of V6, which means:
 V9 = 1.1 × V6 
Now, the important part is understanding how to calculate the total value of transactions.
It’s simply:
 Value = Number of transactions × Average value per transaction 
So,
V9 = N9 × C9avg
V6 = N6 × C6avg
Substitute these into the earlier equation:
 N9 × C9avg = 1.1 × N6 × C6avg 
Now plug in the values:
 20 × C9avg = 1.1 × 22 × C6avg 
Simplify the right-hand side:
 20 × C9avg = 24.2 × C6avg 
Divide both sides by 20:
 C9avg = 1.21 × C6avg 
This means that the average value per transaction in 2009 was  21% higher  than in 2006

gabgol1998 · Answer

The best way to solve this problem is:

Plug in values.

Let's say that the price of every transaction (arithmetic mean) is $100.

$100 x 22 transactions = 2200 total value of all transactions in 2006.

$100 x 20 transactions = 2000 total value of all transactions in 2009.

What if the total value in 2006 is now the new value in 2009, but increased by 10 percent?

$2200 x 1,10 = $2420.

How much should be the price of every transaction now in order to reach the new value considering I have a fixed number of 20 transations in 2009?

$2420/20 = $121.

The increase is (21/100)*100 = 21 percent.

Jayatigarg31 · Answer

Why 1.1x/20?

Bunuel · Answer

1.1x is used because the 2009 total value is 10 percent more than x.

20 is used because the 2009 number of credit card transactions is 20, so the 2009 average is 1.1x divided by 20.

In Country C, the number of transactions made by various noncash metho

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